<HTML><HEAD><TITLE>rem(+Number1, +Number2, -Result)</TITLE>
</HEAD><BODY>[ <A HREF="index.html">Arithmetic</A> | <A HREF="../../index.html">Reference Manual</A> | <A HREF="../../fullindex.html">Alphabetic Index</A> ]
<H1>rem(+Number1, +Number2, -Result)</H1>
Evaluates the remainder Number1 rem Number2 and unifies the resulting value
with Result.


<DL>
<DT><EM>Number1</EM></DT>
<DD>Integer.
</DD>
<DT><EM>Number2</EM></DT>
<DD>Integer.
</DD>
<DT><EM>Result</EM></DT>
<DD>A variable or integer.
</DD>
</DL>
<H2>Description</H2>
   This predicate is used by the ECLiPSe compiler to expand evaluable
   arithmetic expressions.  So the call to rem(Number1, Number2, Result) is
   equivalent to
<PRE>
    Result is Number1 rem Number2
</PRE>
    which should be preferred for portability.
<P>
    The modulus operation computes the remainder corresponding to the
    truncating division //.  The following relation always holds:
<PRE>
    X =:= (X rem Y) + (X // Y) * Y.
</PRE>
    The result Result is either zero, or has the same sign as Number1.  The
    absolute value of Result does not depend on the signs of the arguments.
<P>
   In coroutining mode, if Number1 or Number2 are uninstantiated, the call
   to rem/3 is delayed until these variables are instantiated.
<P>
   See also the mod operation, whose result only differs when the arguments
   have opposite signs.

<H3>Modes and Determinism</H3><UL>
<LI>rem(+, +, -) is det
</UL>
<H3>Exceptions</H3>
<DL>
<DT><EM>(4) instantiation fault </EM>
<DD>Number1 or Number2 is not instantiated (non-coroutining mode    only).
<DT><EM>(5) type error </EM>
<DD>Number1 or Number2 is a number but not an integer.
<DT><EM>(20) arithmetic exception </EM>
<DD>Illegal arithmetic operation: Number2 is zero
<DT><EM>(24) number expected </EM>
<DD>Number1 or Number2 is not of a numeric type.
</DL>
<H2>Examples</H2>
<PRE>
Success:
      X is 10 rem 3.		(gives X = 1)

      rem( 10,  3,  1).
      rem(-10,  3, -1).
      rem( 10, -3,  1).
      rem(-10, -3, -1).

      rem( 11,  3,  2).
Fail:
      rem(1, 2, 3).
      rem(6, 2.0, 3.0).
      rem(5, 2, r).
Error:
      rem(A, 2, 6).              (Error 4).
      rem(2, 0, Result).         (Error 20).
      rem(4 + 2, 2, 12).         (Error 24).
</PRE>
<H2>See Also</H2>
<A HREF="../../kernel/arithmetic/is-2.html">is / 2</A>, <A HREF="../../kernel/arithmetic/FF-3.html">// / 3</A>, <A HREF="../../kernel/arithmetic/mod-3.html">mod / 3</A>
</BODY></HTML>
